1. The Field of the Invention
This invention relates to a probe card for testing semiconductor devices. More particularly, this invention relates to a probe card for testing semiconductor devices that has a simplified circuit configuration for internal transmission of electrical signals and enhances its fabrication and assembly characteristics to guarantee improved reliability to productivity and performance.
2. Description of the Related Art
Generally, the process for manufacturing a semiconductor device includes a fabrication process for forming patterns on a wafer and an assembly process for assembling the pattern-formed wafer into chips, and additionally an electrical die sorting (hereinafter referred to as “EDS”) process provided between the fabrication and assembly processes to test the electrical characteristics of the individual chips constituting the wafer.
The EDS process is discriminating defectives among the component chips of the wafer, i.e., applying electrical signals to the component chips of the wafer and determining the defectiveness of the chips from the feedback signals checked. The facility provided for this EDS process is called “probe equipment”.
In the probe equipment, a configuration for applying electrical signals in direct contact with the pattern of each chip on the wafer is called “probe card”.
The testing for electrical characteristics of a semiconductor wafer using the probe card is measuring the electrical characteristics of the semiconductor wafer by making the needles of the probe card in contact with the electrode pad of each device and applying a specific current through the needles.
When the testing result for a semiconductor device using the probe card is found out “good”, the semiconductor device is fabricated into a complete product by the subsequent process such as packaging.
In accordance with the recent trends towards high integration and extreme miniaturization of semiconductor devices and size increase of wafers for the purpose of improved productivity, there is a demand for testing equipment appropriately copying with such trends of technology for the testing of the semiconductor devices.
In other words, the most important real problem in the technological development of the probe card is appropriately coping with the testing of semiconductor devices that are fabricated in a larger number with its miniaturization from a larger wafer, and testing a larger number of semiconductor devices in a simultaneous manner.
The probe cards include a main board, a sub board, a means for interfacing the sub board, and needles for transmission of electrical signals from the sub board to the semiconductor device.
Namely, the configurations of the interface means, the sub board, the needles, and the needle guide are improved so as to reduce circuit patterns from the main board to the sub board with more enhanced electrical characteristics.
According to the aforementioned patents of the applicant of the present invention, the configuration of the interface means between the main board and the sub board is more simplified to achieve an accurate transmission of electrical signals from the main board to the sub board, and the needles are changed from a wire type to a fine blade type so as to appropriately cope with high-density and high-integration semiconductor device patterns.
In particular, a number of micro needles are formed simultaneously by a fine-pattern forming process for the fabrication of semiconductor devices, such as an etching process, thereby facilitating the testing of the electrical characteristics of the semiconductor devices having a fine pattern.
However, the conventional interface means for transmission of electrical signals between the main board and the sub board has no or little connection flexibility.
Namely, the interfacing means between the main board and the sub board is mostly formed in the bar or wire form having a cross section shaped like a circle or a circle-like ellipsoid. The top and bottom ends of the interfacing means are associated with the main board and the sub board, respectively, by welding or soldering for transmission of electrical signals.
Such an interface means has no flexibility at all, so a vertical impact due to the contact with the connection terminals of the semiconductor device in use may cause damages on the welded or soldered part of the circuit board, particularly damaging the main board that is a relatively expensive component part.
Once the main board, the interface means, and the sub board are combined together firmed by welding or soldering, they cannot be separated from one another, causing an uneconomical problem in regard to the difficulty of repair.
The flatness of the sub board is of a great importance in achieving a stable connection, but there is no configuration for guaranteeing the flatness. It is therefore possible to check a normal connection state only through a testing for checking the power output from the respective connection terminals by applying the power to the main board in the complete assembly. With a defective detected in the testing in the assembly situation, there is no way but do away with the probe card due to the difficulty of disassembly and repair, causing a great economic loss.